package org.miniframework.mvc;

import lombok.Getter;
import lombok.Setter;
import lombok.extern.slf4j.Slf4j;
import org.miniframework.mvc.processor.RequestProcessor;
import org.miniframework.mvc.render.DefaultResultRender;
import org.miniframework.mvc.render.InternalErrorResultRender;
import org.miniframework.mvc.render.ResultRender;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.util.Iterator;

/**
 * 1.以责任链的模式执行注册的请求处理器
 * 2.委派给特定的Render实例对处理后的结果进行渲染
 */
@Slf4j
@Setter
@Getter
public class RequestProcessorChain {
    // 请求处理器迭代器
    private Iterator<RequestProcessor> requestProcessorIterator;
    // 请求 request
    private HttpServletRequest request;
    // 请求 response
    private HttpServletResponse response;
    // http请求方法
    private String requestMethod;
    // http请求路径
    private String requestPath;
    // http响应状态码
    private int responseCode;
    // // http请求方法请求结果渲染器
    private ResultRender resultRender;

    public RequestProcessorChain(Iterator<RequestProcessor> iterator, HttpServletRequest req, HttpServletResponse resp) {
        this.requestProcessorIterator = iterator;
        this.request = req;
        this.response = resp;
        this.requestMethod = req.getMethod();
        this.requestPath = req.getPathInfo();
        this.responseCode = HttpServletResponse.SC_OK;
    }

    /**
     * 责任链模式依次调用请求处理器对请求进行处理
     */
    public void doRequestProcessorChain(){
        try {
            // 1.通过迭代器遍历注册的请求处理器实现类列表
            while (requestProcessorIterator.hasNext()){
                // 2.直到某个请求处理器执行后返回false为止
                if (!requestProcessorIterator.next().process(this)){
                    break;
                }

            }
        } catch (Exception e) {
            // 3.期间如果出现异常，则交由内部异常渲染器处理
            this.resultRender = new InternalErrorResultRender(e.getMessage());
            log.info("doRequestProcessorChain error.",e);
        }
    }

    /**
     * 执行处理器
     */
    public void doRender() {
        // 1.如果请求处理器实现类均未选择合适的渲染器，则使用默认的
        if (this.resultRender == null){
            this.resultRender = new DefaultResultRender();
        }
        try {
            // 2.调用渲染器的render方法对结果进行渲染
            this.resultRender.render(this);
        } catch (Exception e) {
            log.info("doRender error.",e);
            throw new RuntimeException(e);
        }
    }
}
